Cadaveric osseous and osteoarticular allograft transplants have been used in the treatment of malignant and aggressive bone tumors in 45 patients with general early success (follow-up of up to 6 years). Numerous questions remain, however, regarding the immunology, cryopreservation, long-term fate, techniques of surgery and indications of use of the technique. The investigators propose an in depth study of the biology of skeletal allograft transplantation in order to made the technique a safe, reliable and more uniformly successful modality, not only for the treatment of bne tumors but other bone and joint disease states. The studies include: 1. Continued retrospective and prospective study of human recipients to assess long-term fate of the graft and immunologic response of the host. 2. Performance of animal experiments drected at improved preservation of cartilage and joint function; more rapid incorporation of the bony portion of the graft; and diminished host immunologic response. 3. Performance of laboratory studies to devise optimal techniques for cryopreservation of bone, cartilage and tendon. To achieve these goals a variety of clinical, radiographic, radioisotopic, biochemical and immunologic studies will be peformed on the patients and experimental models. Bone and cartilage from the animal models will be studied by histologic, histochemical biochemical and metabolic techniques.